Patent GB-585977-A (GB)
Title: Improvements in "back-up" bars as used in welding operations
IPC: B23K9/035
Filed: 1944-11-10
Abstract: 585,977. Uniting by fusion. STOUT, W. H. Nov. 10, 1944, No. 22159. [Class 83 (iv)] A back-up bar for use in seam welding comprises a succession of juxtaposed segments of block-like form, each consisting of a number of relatively movable laminations and means for retaining the segments in close conformity with the seam during welding. The bar may thus adjust itself to variations in the position of the parts being welded due to warpage caused by welding heat &c. and thus to prevent escape of molten metal from the seam. A succession of non-bendable blocks 21 such as of refractory material are placed end to end on a flexible sheet metal plate 20 which is pressed up by a number of springs 30 against the flanges 16, 16<1> of a box member 15 mounted on a jack or on supports 12 through wedges 13, which press the blocks against the underside of the plates 10, 10<1 >to be welded. The sheets may have transverse slits at positions corresponding to the ends of the blocks, which consist of outside and inside pairs-of laminations 25a, 25b, the inner laminations being shorter so as to provide space for a pair of bevelled inserts 50 of clay, soap-stone or other heat-resisting material pressed against the inner side of the joint. The ends of the blocks may be at a slight acute angle, Fig. 14, to ensure that when they are in close juxtaposition the bar may be arched upwardly to a considerable extent without opening gaps across the top surfaces of the bar. The blocks are held laterally against the flange 17 by a flexible metal strip 42 engaged by springs 45 mounted on posts 41, the laminations being held in contact with each other by springs 59<1>. Springs 57 are inserted in recesses in the base of the parts 25b to ensure the holding of the blocks against the plate edges. Welding is effected by arc or flame down through the edges of the plates to form the bead on the underside of the plate during the main welding operation. In another form, the underside of the plate 20 is engaged by cross-bars 32, Fig. 3, pivoted to rods 33 passing through the springs 30<1>. The strips 42 and springs 45 may also be replaced by a number of leaf springs 60. In a further form, the plate 20, Fig. 6, is supported by two rows of coiled springs 30a each surrounding a headed vertical rod 33a slidable in sleeves 72 fixed to the bottom of the box 15. The assembly of blocks may also be held together by rods 82, 82<1> passing through bars 81 at each end and having at one end nuts and compression springs, or by similarly mounted rods passing through holes in the laminations. In welding plates of different thickness, shims may be inserted under the laminations placed under the thinner plate. In another form, the blocks are mounted on base-plates 90, Fig. 10, mounted in pairs on bars 91, themselves mounted in pairs on bars 92 supported on a bar 93 held up by a central support 94 such as a spring steel member, jack, &c. In welding a horizontal seam in a vertical wall, Fig. 11, a back-up bar of the kind described is applied along one side of the plates and along the other side refractory members 99, 99<1>, 100, 102 are carried in an angle bar 98, the member 99<1> being grooved at 101 to receive the filler metal.